Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharid...
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1990
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v172_n3_p1640_Uttaro http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro |
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paper:paper_00219193_v172_n3_p1640_Uttaro2023-06-08T14:43:08Z Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens glucan phosphoglucomutase polysaccharide article biosynthesis defective mutant nonhuman priority journal Rhizobium radiobacter Agrobacterium tumefaciens Medicago sativa Rhizobium Sinorhizobium meliloti The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. We tested the possibility that the pleiotropic ExoC phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic pathways. Cytoplasmic extracts from wild-type A. tumefaciens and from exoC mutants of A. tumefaciens containing a cloned wild-type exoC gene synthesized in vitro UDP-glucose from glucose, glucose 1-phosphate, and glucose 6-phosphate. Extracts from exoC mutants synthesized UDP-glucose from glucose 1-phosphate but not from glucose or glucose 6-phosphate. Membranes from exoC mutant cells synthesized β(1-2)glucan in vitro when exogenous UDP-glucose was added and contained the 235-kilodalton protein, which has been shown to carry out this synthesis in wild-type cells. We conclude that the inability of exoC mutants to synthesize β(1-2)glucan is due to a deficiency in the activity of the enzyme phosphoglucomutase (EC 2.7.5.1), which in wild-type bacteria converts glucose 6-phosphate to glucose 1-phosphate, an intermediate in the synthesis of UDP-glucose. This interpretation can account for all of the deficiencies in polysaccharide synthesis which have been observed in these mutants. 1990 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v172_n3_p1640_Uttaro http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
glucan phosphoglucomutase polysaccharide article biosynthesis defective mutant nonhuman priority journal Rhizobium radiobacter Agrobacterium tumefaciens Medicago sativa Rhizobium Sinorhizobium meliloti |
| spellingShingle |
glucan phosphoglucomutase polysaccharide article biosynthesis defective mutant nonhuman priority journal Rhizobium radiobacter Agrobacterium tumefaciens Medicago sativa Rhizobium Sinorhizobium meliloti Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| topic_facet |
glucan phosphoglucomutase polysaccharide article biosynthesis defective mutant nonhuman priority journal Rhizobium radiobacter Agrobacterium tumefaciens Medicago sativa Rhizobium Sinorhizobium meliloti |
| description |
The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. We tested the possibility that the pleiotropic ExoC phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic pathways. Cytoplasmic extracts from wild-type A. tumefaciens and from exoC mutants of A. tumefaciens containing a cloned wild-type exoC gene synthesized in vitro UDP-glucose from glucose, glucose 1-phosphate, and glucose 6-phosphate. Extracts from exoC mutants synthesized UDP-glucose from glucose 1-phosphate but not from glucose or glucose 6-phosphate. Membranes from exoC mutant cells synthesized β(1-2)glucan in vitro when exogenous UDP-glucose was added and contained the 235-kilodalton protein, which has been shown to carry out this synthesis in wild-type cells. We conclude that the inability of exoC mutants to synthesize β(1-2)glucan is due to a deficiency in the activity of the enzyme phosphoglucomutase (EC 2.7.5.1), which in wild-type bacteria converts glucose 6-phosphate to glucose 1-phosphate, an intermediate in the synthesis of UDP-glucose. This interpretation can account for all of the deficiencies in polysaccharide synthesis which have been observed in these mutants. |
| title |
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| title_short |
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| title_full |
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| title_fullStr |
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| title_full_unstemmed |
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens |
| title_sort |
biochemical characterization of avirulent exoc mutants of agrobacterium tumefaciens |
| publishDate |
1990 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v172_n3_p1640_Uttaro http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro |
| _version_ |
1768541877059977216 |